Pyrocatechol

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

The experimental conditions and the obtained results were well described. A longer duration period (96h) than that recommended in the current guideline (72h) was applied. There was no analytical monitoring of the test substance concentration.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

exposure duration, temperature, factor of increase of the cellular density in the control for culture type I.

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

not specified

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Catechol was added to the culture medium directly before inoculation.
- Controls: Yes, test water without test item.
No further data.

Test organisms (species):

Chlorella vulgaris

Details on test organisms:

TEST ORGANISM
- Common name: Chlorella vulgaris
- Strain: Chlorella BB
- Source (laboratory, culture collection): from a synchronic culture from the Department for biochemistry and biophysics, Silesian University Medical School.
- Method of cultivation: The algae were cultured in Erlenmayer's flasks (750 cm3) in 200 cm3 suitable medium at constant light (about 5000 lux) and constant stirring (magnetic stirrers), at room temperature (17 - 27°C). The type I cultures were contained in flasks closed with microbiological corks, with modified Kühl-Lorenzen medium (pH 6.5). The type II cultures were contained in flasks closed tightly with groun corks in the medium according to Avramova with the addition of 5 g NaHCO3 per 1 dm3 of medium (pH 8.5).
- Other information:
* Type I cultures:
Growth indexes at 1, 7 and 14 days: 1.49 (+/-0.17), 7.44 (+/- 0.54) and 10.1 (+/- 0.14)
* Type II cultures:
Growth indexes at 1 and 7 days: 1.23 (+/- 0.1) and 23.02 (+/- 0.39)

ACCLIMATION
The investigated Chlorella BB strain was adapted for some days to the conditions corresponding to type I and II cultures in special maternal cultures.

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

No data

Test temperature:

17 - 27°C

pH:

6.5 (Type I cultures)
8.5 (Type II cultures)

Dissolved oxygen:

No data

Salinity:

Not applicable

Nominal and measured concentrations:

Catechol concentrations tested were:
58.4, 87.0, 131.0, and 196.0 mg/L for type I cultures.
13.2, 26.4, 52.9, and 105.7 mg/L for type II cultures.
In the publication, concentrations were expressed in mmol/dm3. They were converted in mg/L using a molecular weight of 110.1122 mol/L.

Details on test conditions:

TEST SYSTEM
- Test vessel:
* Type I culture: flasks closed with microbiological corks
* Type II culture: flasks closed tightly with ground corks
- Initial cells density: 5 mln cells per 1 cm3 of culture medium
- Control end cells density:
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
No further data

GROWTH MEDIUM
- Medium used:
* Type I culture: modified Kühl - Lorenzen medium
* Type II culture: medium according to Avramova with the addition of 5 g NaHCO3 per 1 dm3 medium
No further data

TEST MEDIUM / WATER PARAMETERS
- Culture medium different from test medium: No
No further data

OTHER TEST CONDITIONS
- Photoperiod: constant light
- Light intensity and quality: 5000 lux
No further data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: The density of the algal suspension were measured using Bürker's hemocytometer. The cell population, the growth curves of the cultures and the time necessary for reaching the maximal cell population in the stationary phase of growth were determined.
No further data.

TEST CONCENTRATIONS
- Spacing factor for test concentrations:
* Type I culture: 1.5
* Type II culture: 2
No further data.

Reference substance (positive control):

not specified

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

22 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

for Type II cultures

Remarks on result:

other: 95%CL: 13.2-36.3 mg/L

Details on results:

Type II cultures:
The cell concentration in the control cultures increased by a factor of 6 within 72 h, and by a factor of 18.5 within 96 h (validity criteria: the factor of biomass increase should be at least 16 at the end of the test period). The growth was exponential.

Type I cultures:
For this culture type, a 96h-EC50 = 111.1 mg/L was found. However, the cell concentration in the control increased by a factor of 2 within 72 h, and by a factor of 2.5 within 96 h. The validity criteria was not fulfilled, and a reliability 3 was attributed to this experiment.

Reported statistics and error estimates:

The EC50 values were determined by Morrison's probit method on the fourth day (at the 96th hour).

Validity criteria fulfilled:

not specified

Conclusions:

Catechol was harmful for Chlorella vulgaris under the tested conditions.

Executive summary:

In a 96-hour study (Majnusz, 1994), the toxicity of the test item Catechol was evaluated on the algal strain Chlorella vulgaris.

The main criterion measured was the EC50, a statistically derived concentration resulting in 50% reduction of the average specific growth rate.

The 96-hour EC50 was 22 mg/L.

Based on these results, Catechol is considered as harmful to algae.

Description of key information

The 96h-EC50 was 22 mg/L based on the growth rate of Chlorella vulgaris.
Catechol is considered as harmful to algae under the tested conditions.

Key value for chemical safety assessment

EC50 for freshwater algae:

22 mg/L

Additional information

Only one study (Majnusz, 1994) was reliable, with a score of 2 according to Klimisch. It was selected as a key study, because it was well described and conducted similarly to the OECD guideline 201. In this study, the acute toxicity of the test item catechol was evaluated in the algal strain Chlorella vulgaris during 96 hours. The main criterion measured was the EC50, a statistically derived concentration resulting in 50% reduction of the average specific growth rate. The 96-hour EC50 was 22 mg/L. There is no indication allowing to know whether the validity criteria were fulfilled. Based on these results, Catechol is considered as harmful to algae.

Other studies were not well described, or not conducted according to recognized guidelines and were all scored as reliability 3.